From b5a0349e6e660ddeb92bec9e4a2cd53665930b1e Mon Sep 17 00:00:00 2001
From: Vladimir Enchev <vladimir.enchev@gmail.com>
Date: Sat, 11 Apr 2026 09:58:00 +0300
Subject: [PATCH] Add custom CssPath to RadzenTheme and its using ThemeService

Based on #2523 by @trucidare
Closes #2523
Closes #2354
---
 Radzen.Blazor.Tests/ThemeTests.cs  | 95 ++++++++++++++++++++++++++++++
 Radzen.Blazor/RadzenTheme.razor.cs |  9 ++-
 Radzen.Blazor/ThemeService.cs      | 20 ++++++-
 3 files changed, 122 insertions(+), 2 deletions(-)
 create mode 100644 Radzen.Blazor.Tests/ThemeTests.cs

diff --git a/Radzen.Blazor.Tests/ThemeTests.cs b/Radzen.Blazor.Tests/ThemeTests.cs
new file mode 100644
index 000000000..f2677c21b
--- /dev/null
+++ b/Radzen.Blazor.Tests/ThemeTests.cs
@@ -0,0 +1,95 @@
+using Bunit;
+using Microsoft.Extensions.DependencyInjection;
+using Xunit;
+
+namespace Radzen.Blazor.Tests
+{
+    public class ThemeTests
+    {
+        [Fact]
+        public void Theme_Renders_Embedded_Default_CssPath()
+        {
+            const string path = "_content/Radzen.Blazor/css";
+
+            using var ctx = new TestContext();
+            ctx.Services.AddScoped<ThemeService>();
+
+            var component = ctx.RenderComponent<RadzenTheme>(parameters =>
+            {
+                parameters.Add(p => p.Theme, "material");
+            });
+
+            Assert.Contains(path, component.Markup);
+        }
+
+        [Fact]
+        public void Theme_Renders_Non_Embedded_Default_CssPath()
+        {
+            const string path = "\"css";
+
+            using var ctx = new TestContext();
+            ctx.Services.AddScoped<ThemeService>();
+
+            var component = ctx.RenderComponent<RadzenTheme>(parameters =>
+            {
+                parameters.Add(p => p.Theme, "awesome");
+            });
+
+            Assert.Contains($"{path}/awesome-base.css", component.Markup);
+        }
+
+        [Fact]
+        public void Theme_Renders_Non_Embedded_Custom_CssPath()
+        {
+            const string path = "_content/custom-assembly/css";
+
+            using var ctx = new TestContext();
+            ctx.Services.AddScoped<ThemeService>();
+
+            var component = ctx.RenderComponent<RadzenTheme>(parameters =>
+            {
+                parameters.Add(p => p.CssPath, path);
+                parameters.Add(p => p.Theme, "my-light");
+            });
+
+            Assert.Contains(path, component.Markup);
+        }
+
+        [Fact]
+        public void Theme_Renders_Embedded_CssPath_For_Embedded_Themes()
+        {
+            const string path = "_content/Radzen.Blazor/css";
+            const string customPath = "_content/custom-assembly/css";
+
+            using var ctx = new TestContext();
+            ctx.Services.AddScoped<ThemeService>();
+
+            var component = ctx.RenderComponent<RadzenTheme>(parameters =>
+            {
+                parameters.Add(p => p.CssPath, customPath);
+                parameters.Add(p => p.Theme, "material");
+            });
+
+            Assert.Contains(path, component.Markup);
+            Assert.DoesNotContain(customPath, component.Markup);
+        }
+
+        [Fact]
+        public void Theme_WcagHref_Uses_Custom_CssPath()
+        {
+            const string path = "_content/custom-assembly/css";
+
+            using var ctx = new TestContext();
+            ctx.Services.AddScoped<ThemeService>();
+
+            var component = ctx.RenderComponent<RadzenTheme>(parameters =>
+            {
+                parameters.Add(p => p.CssPath, path);
+                parameters.Add(p => p.Theme, "my-light");
+                parameters.Add(p => p.Wcag, true);
+            });
+
+            Assert.Contains($"{path}/my-light-wcag.css", component.Markup);
+        }
+    }
+}
diff --git a/Radzen.Blazor/RadzenTheme.razor.cs b/Radzen.Blazor/RadzenTheme.razor.cs
index d48e104ef..4c1b720c4 100644
--- a/Radzen.Blazor/RadzenTheme.razor.cs
+++ b/Radzen.Blazor/RadzenTheme.razor.cs
@@ -20,11 +20,17 @@ namespace Radzen.Blazor
         public string? Theme { get; set; }
 
         /// <summary>
-        /// When set to true the icon font will be preloadd.
+        /// When set to true the icon font will be preloaded.
         /// </summary>
         [Parameter]
         public bool PreloadIconFont { get; set; } = true;
 
+        /// <summary>
+        /// Custom css path. If set, it overwrites the default path.
+        /// </summary>
+        [Parameter]
+        public string? CssPath { get; set; }
+
         /// <summary>
         /// Enables WCAG contrast requirements. If set to true additional CSS file will be loaded.
         /// </summary>
@@ -52,6 +58,7 @@ namespace Radzen.Blazor
         {
             persistentComponentState = ServiceProvider.GetService<PersistentComponentState>();
 
+            ThemeService.SetCssPath(CssPath);
             theme = ThemeService.Theme ?? GetCurrentTheme();
             wcag = ThemeService.Wcag ?? Wcag;
 
diff --git a/Radzen.Blazor/ThemeService.cs b/Radzen.Blazor/ThemeService.cs
index 79ac35973..f6ad72289 100644
--- a/Radzen.Blazor/ThemeService.cs
+++ b/Radzen.Blazor/ThemeService.cs
@@ -405,6 +405,11 @@ namespace Radzen
         /// </summary>
         public bool? RightToLeft { get; private set; }
 
+        /// <summary>
+        /// Custom css path. If set, it overwrites the default path.
+        /// </summary>
+        public string? CssPath { get; private set; }
+
         /// <summary>
         /// Raised when the theme changes.
         /// </summary>
@@ -473,7 +478,11 @@ namespace Radzen
 
         internal string WcagHref => $"{Path}/{Theme}-wcag.css?v={Version}";
 
-        private string Path => Embedded ? $"_content/Radzen.Blazor/css" : "css";
+        private string Path => Embedded
+            ? $"_content/Radzen.Blazor/css"
+            : !string.IsNullOrEmpty(CssPath)
+                ? CssPath
+                : "css";
 
         internal bool Embedded => Theme switch
         {
@@ -517,5 +526,14 @@ namespace Radzen
                 TriggerChange = true
             });
         }
+
+        /// <summary>
+        /// Sets a specific css path to the theme service.
+        /// </summary>
+        /// <param name="cssPath">New css path to look for themes.</param>
+        public void SetCssPath(string? cssPath)
+        {
+            CssPath = cssPath;
+        }
     }
 }
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